TUSB4020BI: What would happen if D+/D- are left disconnected?

Roy Hsu

Genius 9350 points

Part Number: TUSB4020BI

Hi there,

My customer is evaluating TUSB4020Bl in a 3D camera design.

At system startup, the charger IC (Running on BC or QC standard) needs to negotiate with the host using D+/D-.

During this period, the D+/D- lines need to be disconnected from TUSB4020Bl.

After negotiation, the D+/D- lines will be connected back to TUSB4020Bl via an USB switch.

During the above process, the D+/D- lines will be open with Vbus powered.

Therefore, I'd like to know what would happen if D+/D- are left disconnected when Vbus is powered?

Thank you!

Best regards,

Roy Hsu

over 8 years ago

0 JMMN over 8 years ago

TI__Guru 60870 points

Hi Roy,

Is the disconnect D+/D- on the upstream port or one of the downstream ports?

Regards,
JMMN

0 Roy Hsu over 8 years ago in reply to JMMN

TI__Genius 9350 points

Hi JMMN,

By upstream port, do you mean the device accepting data/power?

If so, TUSB4020 will be on the upstream port.

Thank you!

Best regards,
Roy Hsu

0 JMMN over 8 years ago in reply to Roy Hsu

TI__Guru 60870 points

Hi Roy,

The TUSB4020B will just remain in the USB 2.0 disconnect state with none of the ports connected.

Regards,

JMMN

0 Roy Hsu over 8 years ago in reply to JMMN

TI__Genius 9350 points

Hi JMMN,

Thanks for letting me know!

Best regards,

Roy Hsu

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TUSB4020BI: What would happen if D+/D- are left disconnected?